Electronics Letters
Electronics Letters > 1986 > 22 > 11 > 609 - 610
Electronics Letters > 1990 > 26 > 19 > 1575 - 1576
Electronics Letters > 1992 > 28 > 10 > 923 - 925
Electronics Letters > 1992 > 28 > 17 > 1608 - 1610
Electronics Letters > 1993 > 29 > 15 > 1329 - 1331